Temperature and Pain Perception

Abstract

The sensory modalities of temperature and pain share a common homeostatic thread and a similar afferent neural organization. Sensory precision can be demonstrated under controlled laboratory conditions, but ultimately such precision is secondary to hedonic feelings of pleasantness and unpleasantness that motivate behaviors necessary to maintain the integrity of the organism. Thermal sensations of warmth and coolness are mediated by independent neural systems with differences in sensitivity, spatial summation, intensity, and spatial discrimination. Thermal adaptation is common to both systems. Within a restricted temperature range, feelings of coolness or warmth wane over a period of minutes (e.g. entering a hot bath) and may disappear, replaced by a state of neither warmth nor cold termed thermal neutrality. The hedonic feeling state is determined by a thermoregulatory system that maintains internal temperature. This system receives inputs from the body core and from the skin. If core temperature is disturbed, these inputs result in appropriate autonomic responses, in subjective feelings of unpleasantness (e.g., warm) and in feelings associated with a specific skin temperature (e.g., room temperature is unpleasant, cold air or water is pleasant).